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  本文選題：勵磁涌流 + 內(nèi)部故障�。� 參考：《華南理工大學(xué)》2014年碩士論文

【摘要】：作為電力系統(tǒng)中的重要主設(shè)備之一的變壓器，其運(yùn)行狀況對于系統(tǒng)的安全可靠運(yùn)行具有舉足輕重的作用�？v聯(lián)差動保護(hù)因具有高靈敏性、快速性和明確的選擇性而被用作變壓器主保護(hù)。但勵磁涌流影響變壓器差動保護(hù)的正確動作，如何快速辨別勵磁涌流與內(nèi)部故障已變成提高變壓器差動保護(hù)正確動作率的關(guān)鍵問題。 目前針對區(qū)分勵磁涌流與內(nèi)部故障的研究已經(jīng)取得了一定成效，但是由于電力系統(tǒng)的運(yùn)行狀態(tài)是非常復(fù)雜的以及其他各種干擾因素的影響，現(xiàn)有的方法還存在一些不足。另一方面，考慮到數(shù)學(xué)形態(tài)學(xué)運(yùn)算只涉及加減運(yùn)算和極值運(yùn)算，，并且非常適合于突變信號的特征提取，本文提出了采用數(shù)學(xué)形態(tài)學(xué)快速辨別變壓器勵磁涌流與內(nèi)部故障的方法。該方法是根據(jù)勵磁涌流與內(nèi)部故障電流在波形特征上的區(qū)別，利用數(shù)學(xué)形態(tài)學(xué)提取相應(yīng)的梯度特征和對稱性特征來區(qū)分勵磁涌流和內(nèi)部故障�？紤]到電流波形的復(fù)雜性，該方法由兩部分組成，一部分是不考慮CT飽和情況時的電流識別，目的是快速識別出變壓器內(nèi)部故障使保護(hù)迅速動作以減少故障電流對變壓器的損害，另一部分是考慮CT飽和情況時的電流識別，這可以保證電流識別的可靠性。 為了驗(yàn)證所提方法的可行性和有效性，本文不僅利用PSCAD/EMTDC軟件搭建相應(yīng)模型得到了大量仿真數(shù)據(jù)，還采用了動模實(shí)驗(yàn)得到的仿真數(shù)據(jù)。試驗(yàn)結(jié)果證明了本文所提出方法能夠有效區(qū)分勵磁涌流與內(nèi)部故障，尤其在出現(xiàn)CT飽和、合閘于輕微故障變壓器等情況下，識別速度和可靠性優(yōu)于二次諧波制動原理和間斷角原理這兩種現(xiàn)有使用的方法。 此外，本文還研制了基于FPGA芯片的硬件電路板來實(shí)現(xiàn)所提出的電流識別方法。識別程序具體是運(yùn)行在移植到Nios II的uC/OS II實(shí)時操作系統(tǒng)上的。硬件電路實(shí)現(xiàn)的測試結(jié)果與仿真數(shù)據(jù)驗(yàn)證結(jié)果一致，同時驗(yàn)證了所提出的電流辨別方法在實(shí)現(xiàn)硬件應(yīng)用時的可行性。
[Abstract]:As one of the most important main equipment in power system, the operation condition of transformer plays an important role in the safe and reliable operation of the power system. The longitudinal differential protection is used as the transformer main protection because of its high sensitivity, rapidity and clear selectivity. However, inrush current affects the correct operation of transformer differential protection. How to quickly distinguish inrush current from internal fault has become a key problem to improve the correct operation rate of transformer differential protection. At present, the research on distinguishing inrush current from internal fault has made some achievements. However, due to the complex operation state of power system and the influence of other disturbance factors, there are still some shortcomings in the existing methods. On the other hand, considering that mathematical morphology only involves addition and subtraction operations and extreme operations, and is very suitable for feature extraction of abrupt signals, this paper proposes a method to quickly distinguish inrush current and internal faults of transformer by mathematical morphology. According to the difference between inrush current and internal fault current in waveform characteristics, the gradient feature and symmetry feature are extracted by mathematical morphology to distinguish inrush current from internal fault. Considering the complexity of the current waveform, the method consists of two parts, one is current recognition without considering CT saturation, The purpose of this paper is to quickly identify the internal faults of the transformer and make the protection operate quickly to reduce the damage of the fault current to the transformer. The other part is to identify the current in the case of CT saturation, which can ensure the reliability of the current recognition. In order to verify the feasibility and effectiveness of the proposed method, this paper not only uses PSCAD / EMTDC software to build the corresponding model to obtain a lot of simulation data, but also uses the simulation data obtained from the dynamic simulation experiment. The experimental results show that the proposed method can effectively distinguish inrush current from internal fault, especially in the case of CT saturation and closing on a slight fault transformer. The speed and reliability are better than the second harmonic braking principle and the discontinuous angle principle. In addition, the hardware circuit board based on FPGA chip is developed to realize the proposed current recognition method. The recognition program runs on the UC / OS II real-time operating system transplanted to Nios II. The test results of the hardware circuit are consistent with the simulation data, and the feasibility of the proposed current discrimination method in the implementation of the hardware application is also verified.
【學(xué)位授予單位】：華南理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TM407

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本文編號：2094903